GHSA-8fxq-53rx-ph5f CVE-2026-111933 GO-2026-6265
Coder: Login endpoint user enumeration via timing-defense placeholder in password comparison
- Severity
- 6.3 / 10
- Medium · CVSS 4.0
- Exploit chance (EPSS)
- 0.22%
- Chance of exploitation in the next 30 days. Higher than 13.27% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
2.34.2- Upgrade github.com/coder/coder/v2 to this version or later
Description
Summary
userpassword.Compare() substituted a placeholder hash derived from the well-known string "hunter2" when the stored hash was empty. Submitting "hunter2" therefore matched accounts with no password hash (nonexistent users and SSO-only users) and a subsequent login-type check returned an HTTP 403 that disclosed the account's login type, versus 401 for password users.
Note: Practical exploitation is limited because the timing side channel is noisy and only reveals whether an account exists.
Impact
An unauthenticated attacker could enumerate valid accounts and their authentication provider by submitting logins with the password "hunter2", distinguishing nonexistent users, SSO users (provider revealed) and password users from the response. This aids credential-stuffing and targeted phishing. No authentication bypass or data access resulted.
Patches
The fix derives the timing-defense placeholder from a secure random value that no supplied password can match.
The fix was backported to all supported release lines:
| Release line | Patched version |
|---|---|
| 2.34 | v2.34.2 |
| 2.33 | v2.33.8 |
| 2.32 | v2.32.7 |
| 2.29 (ESR) | v2.29.17 |
Workarounds
None.
References
- Fix: #26205
Credits
We'd like to thank Anthropic's Security Team (ANT-2026-22433) for independently disclosing this issue!
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/coder/coder | all versions |
No fix yet |
| github.com/coder/coder/v2 | >= 2.34.0, < 2.34.2 |
2.34.2 |
| github.com/coder/coder/v2 | >= 2.33.0, < 2.33.8 |
2.33.8 |
| github.com/coder/coder/v2 | >= 2.30.0, < 2.32.7 |
2.32.7 |
| github.com/coder/coder/v2 | < 2.29.17 |
2.29.17 |
| github.com/coder/coder/v2 | < 2.29.17>= 2.30.0, < 2.32.7>= 2.33.0, < 2.33.8>= 2.34.0, < 2.34.2 |
2.29.172.32.72.33.82.34.2 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/coder/coder/v2 Go → 2.34.2
- go
go get github.com/coder/coder/v2@v2.34.2 && go mod tidy
Severity breakdown
CVSS 4.0 6.3
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Attack vector
- Network
- Attack complexity
- High
- Attack requirements
- Present
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- Low
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Not defined
- Scope
- X
CVSS 3.1 3.7
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Weakness
CWE-203: Observable Discrepancy
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
How to prevent it
- Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
- Implementation: Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
CWE-204: Observable Response Discrepancy
The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.
How to prevent it
- Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
- Implementation: Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
References
Packages
Other links
- github.com/coder/coder/security/advisories/GHSA-8fxq-53rx-ph5f
- github.com/coder/coder/pull/26205
- github.com/coder/coder/commit/35a7dc8ab9c7f15ce05d963947823ee31224512f
- github.com/coder/coder/releases/tag/v2.29.17
- github.com/coder/coder/releases/tag/v2.32.7
- github.com/coder/coder/releases/tag/v2.33.8
- github.com/coder/coder/releases/tag/v2.34.2
- vulncheck.com/advisories/coder-before-2.34.2-user-enumeration-via-login-placeholde…
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-h58c-xccx-75m3 Coder: Stored HTML injection via unescaped ApplicationName and LogoURL appearance settings | Medium | Also affects github.com/coder/coder |
| GHSA-qrwj-vh9x-gw5v Coder's workspace agent API insecure redirect handling allowed cross-agent file read and write | High | Also affects github.com/coder/coder |
| GHSA-5wg6-jmq2-53pw Coder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing | Medium | Also affects github.com/coder/coder |
| GHSA-7qw2-f75v-62f7 Coder vulnerable to stored HTML injection via workspace agent logs in AgentLogLine component | Medium | Also affects github.com/coder/coder |
| GHSA-84rm-42xw-mx52 Coder's AI Bridge Proxy skips TLS certificate verification in default configuration | High | Also affects github.com/coder/coder |
| GHSA-wqxv-w64v-5wh6 Suspended Coder users retain access to AI Bridge LLM proxy endpoints | Medium | Also affects github.com/coder/coder |
| GHSA-f5vp-w269-392g Coder vulnerable to denial of service via unbounded request body in AI Bridge provider endpoints | Medium | Also affects github.com/coder/coder |
| GHSA-jqj2-x4c5-jfxm Coder: Devcontainer recreate endpoint missing write authorization allows read-only roles to destroy containers | Medium | Also affects github.com/coder/coder |
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